Hi Christopher,
I hit a snag immediattly after hitting Shift-F9: It was complaining about not being able to find the Windows Unit while recompiling the LCL package.
Had a look at the Project Options and found out you had it locked to Windows.
Removed both ticks under Project Options->Compiler Options->Additions and Overrides that where there and it compiled. The visual aspect of my compiled version is better that what you're distributing. But that's something for another discussion :)
I'm not sure how you're crosscompiling, so I'm not going to offer any solution.
What I do, and it's my choice (not imposing anything at all!), is not really crosscompile. I set a couple of VM's (Linux32, Win32 and Win64 ) and then use them to natively compile the apps.
That way I don't have to choose the Widgets, they get chosen by the defaults on each Lazarus install.
On a last note, I can assert that the app compiles under Lazarus 1.7 FPC 3.0 Linux amd64 :)
Cheers,
Gus
Removed ticks from the selected widgetset in trunk